A conventional power train for vehicles, particularly for heavy industrial machinery such as that used in forestry, landfill operations, agriculture, mining, construction, material handling, tunneling, drilling and other industries, often includes a power source that is operatively connected to the driven traction devices, such as the rear wheels of a wheeled machine, through an axle shaft connected to a final drive assembly. The final drive assembly typically consists of a gear set that is designed to alter the rotational speed and torque transmitted from the axle shaft to the traction devices of the machine. Examples of machines employing such arrangements may include, for example, loaders, motor graders, dozers, excavators, compactors, water trucks, articulated trucks, dump trucks, tractors, material handlers, and similar heavy mobile equipment.
For example, in an off-highway truck or tractor, such as an off-highway dump truck, an engine or other power source may be operatively connected through a transmission to a rear differential that is configured to transmit rotational power to the rear wheels disposed on opposing sides of the machine. The two axle shafts extending from the rear differential may be connected through a sun gear to the final drive including planetary gears, carriers, pins, and additional sun gears, as is well known in the art. Such final drives are configured to provide a reduction in rotational velocity with an accompanying increase in torque delivered to the driven rear wheels of the machine. The final drive typically includes a final drive housing having an external cover plate that can be removed for access to the axle shaft and final drive components. In some configurations, the cover plate may also serve to restrict axial movement of the associated axle shaft during operation. However, this can lead to distortion and wear of both the axle shaft and the cover plate. To resolve this issue, it is known to include a replaceable wear plate that is affixed to the internal surface of the cover plate. The axle shaft is disposed against the wear plate during operation, the axle shaft rotating at a higher velocity than the cover plate and affixed wear plate due to the reductive final drive.
To decrease the time associated with maintenance and replacement of the centrally disposed axle shaft, it is also known to provide a cover plate that includes an outer cover plate and an inner, smaller cover plate, wherein the smaller cover plate may be removed without having to fully drain lubricant from the final drive housing to access and/or remove the axle shaft. A wear plate has been attached to an inner surface of the inner cover plate to engage the axle shaft. In this regard, removing the smaller cover plate also provides a more efficient method for replacement of the wear plate.
While the wear plate can reduce the stresses to the axle shaft and reduce wear to both the axle shaft and an unprotected cover plate, the axle shaft can still be subject to wear, distortional stresses and the associated decreased performance and/or axle failure. The present disclosure is directed to an improved cover plate, thrust plate and bearing assembly that addresses one or more of the problems or shortcomings set forth above.